Say you write a PHP class that needs to call the parent constructor. At first sight, this is simple:
function __construct()
{
parent::__construct();
}

Say you want to pass some arguments to the parent constructor:
function __construct($arg1, $arg2)
{
parent::__construct($arg1, $arg2);
}

Now what do you do if you have default arguments?
function __construct($arg1 = NULL, $arg2 = NULL)
{
if ($arg1 == NULL && $arg2 == NULL) parent::__construct();
elseif ($arg2 == NULL) parent::__construct($arg1);
else parent::__construct($arg1, $arg2);
}
Not pretty, especially if you have many possible arguments. The obvious generalization would be
function __construct()
{
call_user_func_array(array('parent','__construct'), func_get_args());
}
However, this actually fails for two reasons on PHP below version 5.3: func_get_args() cannot be used as a function argument, and call_user_func_array does not treat parent correctly.
So here’s the entire constructor I ended up with that does absolutely nothing but calling the parent function:
function __construct()
{
$args = func_get_args();
if (version_compare(PHP_VERSION, '5.3.0') >= 0)
{
call_user_func_array(array('parent','__construct'), $args);
}
else
{
$refl = new ReflectionObject($this);
$method = $refl->getParentClass()->getConstructor();
$method->invokeArgs($this, $args);
}
}
Seriously, you have to use reflections for this seemingly simple task?!